Inflammation may serve as on of the principle initiators of acute and chronic lung diseases in man. Inflammatory hormones are transiently released into the blood at very low concentrations. Because of their extremely low concentration, lability and destruction within blood and surrounding tissues, detection and quantitation in vivo is difficult. Using isotonic contractions of rat stomach fundus strips, rat duodenum and guinea pig colon the concentration of inflammatory hormones in the perfusate of isolated guinea pig lungs will be determined. Guinea pig lungs will be ventillated, while perfused, with alternating negative pressure in an artificial thorax. The response of the bioassay tissues will be characterized by studies of the biosynthesis of prostaglandins and other vasoactive hormones such as SRS-A. The sequence leading to contraction and the factors necessary for contraction will be established (substrate requirements, inhibition by aspirin and indomethacin and competitive inhibition by analogs of unsaturated fatty acids and prostaglandin intermediaries). Studies will then be undertaken using the lung as the source of the inflammatory hormones by ventilation with air containing air pollutants corresponding to levels of industrial exposure. These studies will provide quantitative estimates of the release of inflammatory hormones by the lung and may lead to a better understanding of inflammation in inhalation toxicology in man.